The complexity of small-vessel vasculitis requires repeated evaluations of disease activity and damage. Clinical assessment, including regular restaging of disease, is important for management of therapeutic interventions; similarly, assessment tools must be standardized and validated for use in the clinical trial setting. The Outcome Measures in Rheumatology group promotes validated outcomes measures for use in trials. Validated tools for use in clinical trials include the Birmingham Vasculitis Activity Score and the Vasculitis Damage Index. In addition, health-related quality of life assessments underscore the importance of patient-ranked issues in assessing and treating vasculitis. Improvements in the clinical treatment of vasculitis will arise from research that is supported by refined and validated assessment tools.